Line sifter



May 10, 1966 s. R. scRuBY ETAL 3,250,389

LINE SIFTER Filed Jan. 28, 1965 WWM\\N MN l .w n 1 Swa\\ s Nu Nm .h//r\\wm n I @,(YF. N\ J\ 1.1 n E Ml 'i A JH QM, WM M ma, a ww s i u M x 1r LV INVENTORJ ATTORNEY United States Patent O 3,250,389 LINE SIFTERStanley R. Scruby and Donald J. Mclver, Houston, Tex., assignors toSystems Engineering and Manufacturing Co., nc., Houston, Tex., acorporation of Delaware Filed Jan. 28, 1955, Ser. No. 428,747 2 Claims.(Cl. 209-250) This invention pertains generally to classifying apparatusand methods and particularly to an improved vibratory sitter and methodsutilized therein, and is a continuation in part of my application,Serial No. 207,190, now abandoned, tiled July 3, 1962.

Various types of sifting or classifying apparatus and methods have beendeveloped for handling pulverized or powdered substances such as our. Inparticular, reciprocating or vibratory sitters of various types havebeen used extensively in prior art devices. For example, United StatesPatent 3,021,952, issued on February 20, 1962, to K. R. Powell, UnitedStates Patent 3,021,953, issued February 20, 1962, to W. A. Brastad etal. disclose sifters or classifying apparatus wherein a reciprocating orvibratory movement is utilized.

Although many of the prior art devices have proven to be satisfactory insome respects, such prior art devices leave much to be desired in theway of optimum design and performance to assure rapid and effectiveclassifying of solid particles having various sizes. Prior artclassifiers have been large since the inputs to the classifiers must bediverted from the in-line path of the incoming material. Also knownclassiiiers have not been pressure tight thereby requiring terminatingand air separating means at the input to the classifier and an air-lockfeeder at the output of the classifier whereby the material isintroduced into another air stream for distance conveying,

Thus, an object of the present invention is to provide an improvedreciprocating, classifying apparatus and to provide improved classifyingmethods.

Another object of the present invention is to provide apparatus andmethods of classifying solid particles Wherein such solid particles areconveyed by the velocity of a source of air under pressure into apressure tight classifying or vibratory apparatus, the air serving as aconveyor and yet not forcing the solid particles through the siftingscreens.

Yet another object of the present invention is to provide improvedclassifying or vibratory apparatus and methods which are characterizedby simplicity, economy, and eifectiveness of operation inasmuch asconventional air separation at the entrance to the classifying apparatusis eliminated as well as recombining mechanism at the discharge of theclassifying apparatus.

Still another object of the present invention is to provide improvedclassifying or vibratory apparatus and methods wherein solid particlesare conveyed by the velocity of a source of air under pressure throughan input into a pressure tight chamber having an outlet for thoseparticles which have not been screened or sifted in the chamber andanother outlet for those particles which have been sifted or screened inthe chamber, with only one air source serving as a conveying media intoand out of the classifying apparatus.

In the drawing, FIGURE 1 is a partial-sectional, elevational view ofapparatus which incorporates the present invention.l

Brietiy stated, the invention provides apparatus an methods foreffectively classifying solid particles which have been conveyed by thevelocity of a source of air ICC under pressure into a pressure tightchamber. The chamber has a deflection member or baie at the input andscreening means' through which particles of a maximum size are sited orscreened as the chamber is motivated by means which cause such chamberto vibrate or oscillate. The chamber has two outlets therein, one forremoval of particles which were not sifted or screened and one forremoval of particles which have been sifted or screened. 0f course aplurality of sifting screensmay be utilized, perhaps with a separateexit for each strata, as desired. The same conveying media which broughtmaterial into the chamber is used for removing the unsifted materialfrom the chamber.

Referring now to the drawing in detail, a pressure tight chamber 10 isshown comprised of a plurality of sections- Which may be identified as abottom 12, top 14, and members 16 and 1S which comprise one end of thechamber. At the opposite end of the chamber are members 20 and 22 whichform the other end of the chamber. Side 24 is disposed between thebottom 12 and top 14 and inasmuch as a section view is shown, anotherside is required to complete the chamber configuration. Although apreferred type of vchamber is shown in the drawing it is to beunderstood that any suitable conliguration of chamber may be utilizedwithout departing from the spirit of the invention, so long as suchchamber is pressure tight. The internal pressure within chamber 10 issubstantially uniform throughout. t

Chamber 10 is divided into an upper portion 26 and a lower portion 28 bya screen or a sifting member 30. The screen or sifting member 30 has aplurality of apertures therein. The size of such apertures is dictatedby the maximum size of particles to be passed through such aperturesinto the lower portion 28 of chamber 10. Screen or sifting member 30 ispositioned at one end of the chamber 10 at point 32 between members 16and 18 and the opposite end of the screen member 30 is positioned onmember 46 at point 34.

The chamber 10 is coupled to a suitable pipe or duct 36 through aiiexible coupling 38. Flexible coupling 38 is attached to duct section40 of the chamber 10.I A source of solid particles is fed through pipe36 into the chamber 10, and deiiected downwardly by baie 41 onto thescreen 30. However, it should be noted that inasmuch as it isundesirable, with respect to the sifting of certain commodities, forexample, flour, production being in accord with appropriate FederalRegulations, for the air to materially assist the solid particles inpassing through screen 30. Said particles pass through said screen bythe vibration imparted to member 10 and/ or by gravity ow. Thus theincoming air-particle mixture should be directed in such as manner as tonot forcefully impinge on the screen with suicient force to blow saidparticles through said screen. In this embodiment, baie 41 serves as thedirectional medium, or force deflector. The solid particles may be ofthe powdered type developed in various processes during the milling orconveying of flour for example. The solid particles are combined with asource of air under pressure (not shown) so that a combination of airand solid particles are brought into the chamber 10 by the velocity ofthe lair under pressure. The pressure at which the particle-aircombination is passed into the chamber 10 may be varied for particularrequirements but a satisfactory velocity has been obtained with a pressure of about tive pounds per square inch.

Discharge outlets 42 and 44 are used lfor removing the sifted orscreened particles and the unsifted particles in a manner to beexplained su-bsequently. Curved member 46 acts as `a divider for thedischarge outlets 42 and 44.

The chamber 1t? is supported near the end having the discharge outletsby a member 48 coupled through a flexible coupling to member 50. Member48 may be welded to the chamber 10 by welds 62 and 64. Member 50 may bewelded to a platform or base 7G by welds 66 and 68. The flexiblecoupling which joins member 48 to member 50 may be constructed of anysuitable material such as a flexible nylon sheet 52. The flexiblecoupling should be rigid enough to support the chamber but also flexibleenough not to break during vibratory movement of the chamber. Sheet 52may be coupled at its upper portion t member 48 by bolts similar to bolt54 which passes through member 48 and sheet 52 and is threadedly coupledto a nut 58. The lower portion of sheet 52 may be coupled to member 50by bolts similar to bolt 56 which passes through member Si) and sheet 52and is threadedly coupled to a nut 60.

Disposed `at the end of chamber 1t) opposite the discharge outlets 42and 44 is a member 84 which is fxedly coupled to the chamber in anysuitable manner. Member 84 is coupled to an eccentric 82 which is drivenby a shaft 80. Shaft 80 is coupled to a member 78 which is concentric toshaft `bil. Member 78 is coupled through suitable coupling means such as`a belt 76 to a motor 72. Motor 72 has a sheave member 74 coupledthereto on which belt 76 is movably attached. Motor 72 and member 7 8may be positioned on platform 7 t) by suitable means 73 and 75,respectively.

Thus during operation of the apparatus, motor '72 is driven by asuitable energy source such as electric power. The motor drives theeccentric means to cause oscillation or vibration lof the chamber means.Provision maybe made to vary the motor speed thereby varying theoscillation period of the chamber means. The positioning of flexiblesheet 52 prevents the oscillatory movement of chamber 10 from beingsubstantially retarded. As the chamber means is oscillated or vibrated,the selected maximum particle size of the solid particles being fed intothe chamber means are passed through the sifter or screen member 32 andinto the lower portion 28 of chamber 10. Inasmuch as the solid particlesare brought into chamber 10 by the velocity of the air under pressure,the reciprocating movement of chamber 10 causes the same particles to besifted and'to continue movement toward exits 42, 44. These siftedparticles are called throughs and are discharged from discharge outlet42. The solid particles which `are too large for passing through thesifter or screen member (also called overs) aredischarged throughdischarge outlet 44 at the end of chamber 10 opposite the inlet 36.Since the chamber is pressure tight, and the pressure substantiallyuniform throughout member 10, the

t volume of air under pressure serves as a discharge media as Well as aninput media thereby eliminating an air separator at the input Iandeliminating mechanism for recombining the particles and air at theoutput.

The present invention overcomes many of the difficulties encounteredpreviously in sifting apparatus and methods inasmuch as in the presentinvention the solid particles are combined with air under pressure toprovide a combination -of air and solid particles as an input to thechamber means. The chamber means is oscillated or vibrated byoscillating means which includes eccentric means well known in the art.The sifting is accomplished by such vibration, in that the incomingair-particle mixture is deviated from directly owing toward .the screen.If the inlet conduit did directly lead toward the screen, the air, underpressure, would exert significant force on the particles and therebyassist the particles, and associated foreign matter, in passing throughthe screen. Flexible couplings allow means to drive the chamber means inan oscillating or vibratory manner. Discharge means are provided for theparticle-air combination which is passed through the sifting means inthe chamber means and for discharging the particle-air combination whichdid not pass through the sifting means. The same source of air velocityserves as a conveying media for discharging particles as well asintroducing particles into the chamber means. Turbulence in the lowerportion of the chamber means is maintained at a minimum therebypreventing blow-back of the sifted particles.

Hereinafter follows a brief explanation of the advantages of the airconveyor operation. It has been mentioned that vessel 10 is intended tohave substantially uniform pressure throughout. Through duct section 4@enter the air-particle mixture, having a certain velocity. Directionalmeans, herein shown as baffle 41, is provided for the purpose ofassuring that the particle mixture will not be forced by air velocitythrough the fine mesh, but will pass therethrough by virtue ofreciprocation and gravity fiow. inasmuch as the air will still have aforce vector direction or velocity after entering the chamber, thisvelocity will be suicient to again permit the overs and throughstorejoin the air carrier in either of ducts 42, 44.V By the means of saidair-conveyor the overs and throughs, or coarses and iines, may, aftersifting, be conveyed to remote points for further operations.

Although a preferred embodiment of the invention has been shown anddescribed, the scope of the invention is defined by the followingclaims. Although such claims may be presented in indented format tofacilitate reading and understanding thereof, such indented format isnot intended as a structural or functional limitation of any of theelements or steps recited in the claims.

We claim:

1. Apparatus adapted for separating particles, said apparatus includingin combination: Chamber means being pressure tight and having screenmeans positioned interiorly of said chamber means, said chamber meanshaving uniform pressure therethrough; conduit means coupled to one endof said chamber means permitting a pressurized mixture of air `and solidparticles to enter said chamber means; means directing the flow of saidpressurizedl mixture into the interior of said chamber in such a mannerthat said air portion of said pressurized mixture does notmateriallyforce said solid particles to pass through said screen means,said directing means being positioned adjacent the juncture of saidchamber land said conduit; oscillating means coupled to one end of saidchamber means to cause preselected particles to be sifted through saidscreen means; first and second discharge means coupled to said chambermeans, said discharge means being so positioned with respect to saidconduit means as to permit pressurized exiting of a mixture of saidpressurized air and unsifted particles through one of said dischargemeans conjointly with pressurized exiting of a mixture of saidpressurized air and sifted particles through the lother of saiddischarge means; said oscillating means includes a platform, a motormounted on one end of said platform, eccentric means coupled to saidmotor and to said chamber means, and a flexible coupling at the otherend of said chamber means connecting said platform to said =chambermeans thereby permitting said chamber means to move in response torotation of said eccentric means. f

2. A method for continuously providing, sifting and exiting anair-particle mixture to and from `a pressure tight chamber comprisingthe steps of:

retaining the internal pressure Within said pressure tight chambersubstantially constant during operation; causing a pressurized mixtureof air and solid particles to be directed into said chamber;

deecting said air-particle mixture from its line of entry into saidchamber so` that the force with which said particles strike internalscreening means within said chamber is insuicient to cause saidparticles to pass through said screening means;

mechanically reciprocating said chamber to cause line portions of saidparticles to pass through said screening means; l

5 6 exiting, under force, coarse portions of said particles ReferencesCited by the Examiner from said chamber through an outlet, 4by means ofUNITED STATES PATENTS a current of air which formed a p-ortion of theinitial air entering Said Chamber; and '398,692 2/1889 Blttlnger 209-318 X exiting, under force, said ne particles from said chani- 51,528,983 3/1925 Montgomery 9*250 X =ber through a further outlet, bymeans of a current 11541399 6/1925 Thomson 9 250 of air which formed aportion of the initial air enter- '310211953 2/1962 Brastad 209-233 Xing said chamber, whereby by virtue of the force P yattributable to saidair current, said iine particles HARRY B'THORNONPHma'y Examiner' may bemoved a substantial distance from said lo R. HALPER, Assistant Examiner.chamber.

2. A METHOD FOR CONTINUOUSLY PROVIDING, SIFTING AND EXITING ANAIR-PARTICLE MIXTURE TO AND FROM A PRESSURE TIGHT CHAMBER COMPRISING THESTEPS OF: RETAINING THE INTERNAL PRESSURE WITHIN SAID PRESSURE TIGHTCHAMBER SUBSTANTIALLY CONSTANT DURING OPERATION; CAUSING A PRESSURIZEDMIXTURE OF AIR AND SOLID PARTICLES TO BE DIRECTED INTO SAID CHAMBER;DEFLECTING SAID AIR-PARTICLE MIXUTE FROM ITS LINE OF ENTRY INTO SAIDCHAMBER SO THAT THE FORCE WITH WHICH SAID PARTICLES STRIKE INTERNALSCREENING MEANS WITHIN SAID CHAMBER IS INSUFFICIENT TO CAUSE SAIDPARTICLES TO PASS THROUGH SAID SCREENING MEANS; MECHANICALLYRECIPROCATING SAID CHAMBER TO CAUSE FINE PORTIONS OF SAID PARTICLES TOPASS THROUGH SAID SCREENING MEANS; EXITING, UNDER FORCE, COARSE PORTIONSOF SAID PARTICLES FROM SAID CHAMBER THROUGH AN OUTLET, BY MEANS OF ACURRENT OF AIR WHICH FORMED A PORTION OF THE INITIAL AIR ENTERING SAIDCHAMBER; AND EXITING, UNDER FORCE, SAID FINE PARTICLES FROM SAID CHAMBERTHROUGH A FURTHER OUTLET, BY MEANS OF A CURRENT OF AIR WHICH FORMED APORTION OF THE INITIAL AIR ENTERING SAID CHAMBER, WHEREBY BY VIRTUE OFTHE FORCE ATTRIBUTABLE TO SAID AIR CURRENT, SAID FINE PARTICLES MAY BEMOVED A SUBSTANTIAL DISTANCE FROM SAID CHAMBER.